Alex may head north to Texas or Louisiana

Tropical Depression Alex has held together fairly well during its passage over Mexico's Yucatan Peninsula, and stands poised to re-intensify back into a tropical storm once it emerges from the coast tonight. Alex brought heavy rains to northern Honduras, Mexico's Yucatan Peninsula, and Belize over the weekend. It was not a good beach day in Cozumel yesterday, as 9.25" of rain fell. Cancun received 2.05" over the weekend, and Belize City received 4.57". Satellite loops show that Alex's heavy thunderstorms are mostly gone near the center, though there are some impressive bands of precipitation well away from the center. There is an upper-level high pressure system a few hundred miles west of Alex, and the clockwise flow air around this high is bringing upper-level winds out of the northwest of about 5 knots over the storm, contributing to the 5 knots of wind shear observed in this afternoon's wind shear analysis from the University of Wisconsin's CIMSS group. Sea Surface Temperatures are very warm, 29 - 30°C, and dry air is currently not a problem for Alex.

Figure 1. Afternoon satellite image of Alex.

Forecast for Alex: which model should you trust?While the track forecast for Alex today through Monday is fairly well-assured, the longer range forecast has become highly uncertain. An increasing number of our reliable models are now indicating Alex may take a more northerly track beginning on Tuesday, with possible landfall on the Texas coast near Galveston on Friday (according to the 8am run of the GFS model) or into western Louisiana on Wednesday (the 8am run of the Canadian model.) The key question remains how Alex will react to the trough of low pressure expected to swing down over the Eastern U.S. on Monday and Tuesday. Most of the models were predicting that the trough would not be strong enough to swing Alex to the north, and several of them continue to predict this. The 8am runs of the NOGAPS and ECMWF models, for example, take Alex into the Gulf coast of Mexico 150 miles south of Texas, on Wednesday. The GFDL and HWRF models split the difference, with the GFDL predicting a Thursday landfall in southern Texas near Brownsville, and the HWRF predicting a Thursday landfall near Corpus Christi. Morris Bender of the GFDL group has just provided me the track forecast from an improved experimental version of the GFDL that shows landfall between Corpus Christi and Galveston. So which model should you trust? Last year, the best performing models at the 3 - 4 day forecast range were the GFS and the Canadian, and these are the models that are currently calling for the more northerly track towards the upper Texas coast and Louisiana. Residents of those areas should review their hurricane preparedness plans and anticipate that Alex could make landfall as early as Wednesday in their vicinity. Residents of the Mexican coast south of Brownsville should make similar plans, as Alex could just as easily hit there.

Re-intensification of Alex is likely once the center of Alex moves offshore, though this will initially be slow due to the current disorganized state of the storm and the relatively low total ocean heat content in the 100-mile-wide stretch of water on the west side of the Yucatan Peninsula. Once Alex moves more than 100 miles from the Yucatan, total heat content of the ocean increases substantially, and Alex will have the opportunity to intensify significantly. A longer time spent over water will give Alex more of a chance to strengthen, and it is possible Alex could intensify into a major hurricane if landfall is delayed until Thursday or Friday. However, Alex's intensification may be limited the farther north it gets, as water vapor satellite images show plenty of dry air over Texas that might interfere with development. Wind shear might also be an issue for Alex if it pushes far enough north, and a slow-moving storm tends to pull up cold water from the depths, limiting intensification. In short, Alex has the potential to intensify into a major hurricane, but there are plenty of roadblocks that make this only a 10% probability in my estimation.

Alex's banding to the west and north keeps filling in... I'm wondering if this storm will have much of a diurnal minimum. Seems ripe to keep stengthening with such low pressure and emergence over water.

I kind of disagree with that rule. Dean and Felix made beelines to the west. Ike curved a little but that was a fairly western-headed storm too.

The conditions drive things, but I do think exceptionally large storms are harder to forecast. We see fewer of them and they have less background data for modeling.

Thanks for reminding people. :) I havent been on here since just after Ike, but I definitely remember all the people who kept saying Ike would never come here because he was too strong and too far north. Can't believe people are still saying that. Statistically it might be the case that strong storms move north, but it i s not something on which to make plans. My rough guess at the moment is anyone west of Mobile should keep a close eye on things, but any storm in the Gulf should be watched by anyone along the Gulf coast.

Quoting pipelines:does anyone have a loop of Ike coming into the gulf from Cuba? I would like to compare the structure/intensification of Ike to Alex at these similar times as I think it will tell us a lot about what Alex may be undergoing. Ike also dropped in pressure after entering the gulf at a fairly fast rate but due to Ike's large size and other unknown variables, it mostly increased the size of the wind field instead of wind speed.

Quoting victoriahurricane:I really think NHC made a mistake in downgrading the system to a tropical depression, probably thinking it's over land, it has to weaken, but it actually strengthened. This never looked at any point in time with his trek over the yucatan any less then a tropical storm and I doubt it fell below that status.

Was not a mistake....winds always fall way behind the pressures in a storm that travels over land due to friction. You can see 960mb hurricanes get downgraded to Cat 1 after landfall with the same pressure.

Alex is an omen of things to come, but not the main event, yet, at least not for the US part of the Gulf. Mexico could very well get a solid Cat 3, but I think the bigger story of Alex is that he's the first one out of the gate.

At first I was bearish on Alex but he did suddenly have a circulation that went from non-existent to simply enormous in a very short period of time. I would expect a Cat 5 to have that kind of breadth of circulation, not a piddly tropical storm. Darby looked puny comparatively, at least on satellite imagery.

Imagine there was not Cuba/Hispanolia and no Yucatan. Alex would have been as big as the Gulf by the time he entered it. DISCLAIMER: At least, that's how it looked to a non-met like me.

does anyone have a loop of Ike coming into the gulf from Cuba? I would like to compare the structure/intensification of Ike to Alex at these similar times as I think it will tell us a lot about what Alex may be undergoing. Ike also dropped in pressure after entering the gulf at a fairly fast rate but due to Ike's large size and other unknown variables, it mostly increased the size of the wind field instead of wind speed.

Quoting GainesvilleGator:Is it Weather456 predicting a N Mexico landfall and Alex will NOT hit Texas?

I think it is premature to be dropping landfall locations for Alex. 3-4 days out there is always a large forecast error spread. This could hit N Mexico but then again it is not wise to rule out other possibilies. Dr. Masters always thows out percentages such as: 70% change of hitting XXX and 30% change of hitting XXX ext.

I hate percentages.....I usually give a section of coastline where I think landfall is likely to occur if it is uncertain and several days out. Yesterday morning I came out and said I thought this would hit Mexico near 25N, and I'm sticking to that for now. Otherwise, people should keep in mine that there is still a lot of uncertainty and there are possibilities for Alex to hit a number of different places. One can never be absolutely certain about a landfall in a situation as fragile as this.

I really think NHC made a mistake in downgrading the system to a tropical depression, probably thinking it's over land, it has to weaken, but it actually strengthened. This never looked at any point in time with his trek over the yucatan any less then a tropical storm and I doubt it fell below that status.